Strategies to Overcome HLA Sensitization and Improve Access to Retransplantation after Kidney Graft Loss

An increasing number of patients waitlisted for kidney transplantation have a previously failed graft. Retransplantation provides a significant improvement in morbidity, mortality, and quality of life when compared to dialysis. However, HLA sensitization is a major barrier to kidney retransplantation and the majority of the highly sensitized patients are waiting for a subsequent kidney transplant. A multidisciplinary team that includes immunogeneticists, transplant nephrologists and surgeons, and adequate allocation policies is fundamental to increase access to a kidney retransplant. A review of Pubmed, ScienceDirect, and the Cochrane Library was performed on the challenges of kidney retransplantation after graft loss, focusing on the HLA barrier and new strategies to overcome sensitization. Conclusion: Technical advances in immunogenetics, new desensitization protocols, and complex allocation programs have emerged in recent years to provide a new hope to kidney recipients with a previously failed graft.

Re-Examining Risk of Repeated HLA Mismatch in Kidney Transplantation

Kidney retransplantation is a risk factor for decreased allograft survival. Repeated mismatched HLA antigens between first and second transplant may be a stimulus for immune memory responses and increased risk of alloimmune damage to the second allograft. Historical data identified a role of repeated HLA mismatches in allograft loss. However, evolution of HLA testing methods and a modern transplant era necessitate re-examination of this role to more accurately risk-stratify recipients. We conducted a contemporary registry analysis of data from 13,789 patients who received a second kidney transplant from 1995 to 2011, of which 3868 had one or more repeated mismatches. Multivariable Cox proportional hazards modeling revealed no effect of repeated mismatches on all-cause or death-censored graft loss. Analysis of predefined subgroups, however, showed that any class 2 repeated mismatch increased the hazard of death-censored graft loss, particularly in patients with detectable panel-reactive antibody before second transplant (hazard ratio [HR], 1.15; 95% confidence interval [95% CI], 1.02 to 1.29). Furthermore, in those who had nephrectomy of the first allograft, class 2 repeated mismatches specifically associated with all-cause (HR, 1.30; 95% CI, 1.07 to 1.58) and death-censored graft loss (HR, 1.41; 95% CI, 1.12 to 1.78). These updated data redefine the effect of repeated mismatches in retransplantation and challenge the paradigm that repeated mismatches in isolation confer increased immunologic risk. We also defined clear recipient categories for which repeated mismatches may be of greater concern in a contemporary cohort. Additional studies are needed to determine appropriate interventions for these recipients.

Re-exposure to mismatched HLA class I is a significant risk factor for graft loss: multivariable analysis of 259 kidney retransplants

BACKGROUND

Kidney retransplants carry increased immunologic risk. One possible contributor to this risk may be re-exposure to human leukocyte antigens (HLA) common to a previous donor but foreign to the recipient. Conflicting publications have assessed this risk, so to examine our experience 259 kidney retransplants were analyzed.

METHODS

A retrospective cohort of retransplant patients from 1973 to 2005 with minimum 12 months follow up was examined. Using multivariable modeling, important confounders were controlled for identifying factors significantly affecting graft survival.

RESULTS

Re-exposure to HLA class I (HLA-A or B) antigens, peak panel reactive antibodies and donor source were the most important determinants of allograft survival, despite a negative conventional or anti-human globulin-augmented T cell crossmatch. We failed to demonstrate that recipient re-exposure to HLA class II (HLA-DR) or positive B cell crossmatch were associated with adverse outcomes. Sample size and molecular versus serologic methods may have influenced the former, while inability to determine antibody specificities may have influenced the latter. Controlling for other variables, the adjusted risk of graft loss associated with re-exposure to HLA class I increased by 71% (P=0.006) and occurred early, consistent with recall of memory cytotoxic T lymphocyte or antibody responses.

CONCLUSIONS

Kidney recipients re-exposed to mismatched HLA class I antigens appear to be at heightened risk of early graft loss. Such patients may benefit from pretransplant identification of donor specific antibodies using solid phase methods and heightened vigilance for acute rejection. Future studies may indicate whether more intensive immunosuppression for these patients is warranted.

A Third Renal Transplantation: Is It Relevant and Is It Worth It?

INTRODUCTION

The aim of this retrospective study was to determine the outcome of third cadaveric renal transplantations performed between 1989 and 2004 among a cohort of 35 patients whose immunosuppression included induction therapy and calcineurin inhibitors. Most patients were highly sensitized with 1 (0-4) HLA (classes I + II) incompatibility between donor and recipient.

RESULTS

The median follow-up time was 57 months (range, 1-190). Fourteen patients experienced delayed graft function that required posttransplantation hemodialysis. The current patient and graft survival rates were 91.4% and 82.8%, respectively. At last follow-up, 6 grafts had been lost: 1 due to primary nonfunction; 1 due to an urinary leak (day 45); 2 deaths with functioning grafts; and 2 chronic allograft nephropathies (CAN) at 85 and 60 months posttransplantation, respectively. Among the 10 patients who experienced acute rejection episodes, half were steroid-sensitive, whereas the others required OKT3 therapy. Overall, when excluding the 2 patients who presented with early loss of their grafts, 13 of 33 patients (39.4%) developed CAN, which led to the graft loss in only 2 cases. The mean creatinine clearance was 57 +/- 23 mL/min at year 5. Of the 35 recipients, 12 (34.3%) developed graft/perigraft complications, among whom 10 (83.3%) required treatment. The most frequent complication was lymphocele (M = 4; 11.4%) or infections that led to rehospitalization (n = 17).

CONCLUSION

Results from third transplantations were encouraging. Thus, despite the organ shortage, a third graft was worth it!